This invention relates to communications apparatus, such as remote data/control apparatus. The invention relates to improvements in communication protocols and communication systems having several remote terminal units and one or more master control centres communicating by radio, serial ports, dedicated lines and/or telephone lines.
Typical applications include, but are not limited to supervisory control and data acquisition (SCADA) for water and waste water systems, electric utility distribution systems, oil and gas pipelines, early warning siren systems, communication control systems, irrigation control systems and roadside emergency callbox systems.